// banner
.carousel {
    img {
        // 源代码height: auto;表述高度随宽度变化
        height: 100% !important;
    }

    @media (max-width: 992px) {
        .item {
            height: 400px;
        }
    }

    @media (max-width: 768px) {
        .item {
            height: 250px;
        }
    }

    @media (min-width: 992px) {
        .item {
            height: 500px;
        }
    }
}

// navbar
.navbar-default{
    background-color: transparent;
    border-color: transparent;
    .container {
        margin-top: 30px;
    }
    .navbar-right {
        margin-top: 15px;
    }
}

.navbar-default .navbar-nav>li>a {
    color: #fff;
    opacity: .6;
}

.navbar-default .navbar-nav>li:first-child>a,
.navbar-default .navbar-nav>li:nth-child(4)>a {
    color: orange;
    position: relative;
}

.navbar-default .navbar-nav>li:nth-child(4)>a::before {
    content: '';
    position: absolute;
    background-image: url(../images/fire.png);
    width: 12px;
    height: 17px;
    top:15px;
    left: 0px;
    background-size: contain;
}

.project {
    text-align: center;
    margin-top: 40px;
    h4 {
        font-size: 30px;
        font-family: Segoe UI Light,Microsoft YaHei,Arial,Helvetica,sans-serif;
        i {
            margin: 0 10px;
        }
    }
    p {
        margin-top: 20px;
        font-size: 16px;
        color: #919191;
    }

    /*
        BootStrap中的栅格系统给的宽度是百分比, 各个元素百分比相加得到的100%,
            因此如果要在栅格系统中两个元素之间添加margin, 此时会使页面布局混乱,
            正确做法应该是: 使用内部元素的padding代替外部盒子之间的margin
    */ 
    div {
        a {
            display: block;
            height: 200px;
            padding: 0 10px;
            background-color: skyblue;
        }
    }
}